Optical solutions are being considered for many high performance computer interconnects because of superior data transmission rates over electrical interconnects. Interconnects are used in computer systems such as in coupling a processor to a volatile memory. Optical interconnects in computer systems provide for higher chip to chip interconnect speeds than current electrical interconnects. For example, electrical interconnects are predicted to have a physical limit of about 15 Gigabits per second chip to chip speed. As data transmission rates increase in electrical interconnects, signal attenuation becomes a limiting factor. Optical interconnects can support speeds of 20 Gigabits per second and beyond.
Complex and data intensive applications that make use of multiprocessor systems continue to require greater data through put and thus higher data transmission rates. Optical signal paths between the processors or the memory can be ideal in such a system. The use of optical interconnects in high-speed multiprocessor system that requires high-speed communication between the individual processors or the memory is preferred. Optical splitters are used in the interconnects to send signals from the processors to two or more memory modules or to other processors.
A limiting factor in the use of optical interconnects is the cost, which is related to the complexity of design and manufacture of optical waveguides in the interconnects. For example, current optical interconnects use three dimensional features to reflect and split light with complex bending mirrors or dielectric stacks. Substrates for the interconnects require complex manufacturing surfaces angled to the z-direction of the substrate. These complicated manufacturing techniques and parts in the interconnects also result in lower than ideal yields, which further increases costs